Electronic and structural properties of rare-earth mono-pnictide (RE-V) nanoparticles in III-V matrices

Embedding semi-metallic rare-earth mono-pnictide (RE-V) nanoparticles into III-V semiconductors enables nanocomposites with a wide range of optical, electrical, and thermoelectric properties. It decreases carrier lifetime, and increases the phonon scattering, leading to lower thermal conductivity but enhanced electrical conduction through electron filtering mechanisms. The common group-V sublattice offers an interesting matching across interfaces of the rock-salt semimetal RE-V (e.g. ErAs) to the zinc-blende semiconductor III-V (e.g. GaAs, AlAs) matrices with similar lattice parameters. Density functional theory (DFT) calculation with the modified Becke-Johnson meta-GGA (mBJ) functional is used to describe the electronic properties of ErAs nanoparticles embedded in GaAs and AlAs. We investigate the stability of different nanoparticle shapes and sizes, from cubic to spherical, deriving a direct correlation between the electron density and atomic density associated with excess metal atoms at the interface. We discuss the band alignment between the RE-V and the III-V and the Fermi level pinning in the gap of the semiconductor, depending on the size and shape of the nanoparticles. Our predictions serve to guide the design of nanocomposite materials with targeted properties.